[ath9k-devel] ath9k performance issues

[Felix Fietkau <nbd@openwrt.org>]

On 2011-04-05 6:19 PM, Bernhard Walle wrote:
> Hello Felix,
>
> * Felix Fietkau<nbd@openwrt.org>  [2011-04-05 17:59]:
>>  On 2011-04-05 5:44 PM, Bernhard Walle wrote:
>>  >
>>  >we're using a PCIe AR9280 card on a Octeon MIPS CPU. The system
>>  >that does the transmission has a high CPU utilization:
>>  >
>>  >iperf in UDP mode with 50M bandwith has ~90 % CPU utilization with a
>>  >high softirq proportion.
>>  >
>>  >Using an Intel card (5300) has a lower CPU utilization (~60 %), but it's
>>  >no option to use it because the Linux driver has no access point mode.
>>  >
>>  >Are there any tweaks to decrease the CPU utilization with the ath9k
>>  >driver? Any recommendations for the application to send the network
>>  >packets more efficient?
>>  What kernel version are you using? Are you using the in-kernel ath9k
>>  or are you using compat-wireless? I have added quite a few
>
> I'm using 2.6.38.1 ath9k which is at ~80 % CPU, starting from 2.6.37.1
> with ~90 % CPU which was still an improvement. Do you think that
> compat-wireless gives still a performance boost?
Not sure. These numbers sound awfully high to me. Maybe you should do 
some profiling to figure out what's using all this CPU time.

>>  Which
>>  performance optimizations over time, as I'm working with much slower
>>  MIPS CPUs than the octeon.
>>  In my tests, a 300 MHz MIPS 24K CPU is good enough for handling
>>  around 90 mbit/s of traffic with only around 70% CPU utilization.
>
> That sounds interesting. Any other optimisations other than using
> compat-wireless?
No. I've pushed all of my enhancements upstream.

- Felix